Technical Field
This description generally relates to sawmills, and more particularly to monitoring the performance and efficiency of lumber manufacturing systems.
Description of the Related Art
The sawmill industry has become largely automated. Full length tree trunks are delivered to sawmills, where they are automatically debarked, scanned and cut into log segments based on their scanned geometry. These log segments are then typically processed at a number of automated stations, depending on the sawmill and the type of wood. These processing stations produce lumber from each log segment, often without any human intervention.
One of the first processing stations in many sawmills is the primary breakdown machine, which processes log segments to produce cants and sideboards. The primary breakdown machine typically includes chip heads for removing slabs as well as one or more band saws for removing sideboards from the log segments. Each log segment may be scanned prior to processing at the primary breakdown machine, and a primary breakdown computer optimizer may then determine an optimal mix of lumber that can be obtained from that log segment based on the scanned geometry. The computer optimizer may then rotate the log segment and control the relative position of the chip heads and band saws to achieve that optimal mix of lumber.
Downstream from the primary breakdown machine, cants may be further processed at a gangsaw to produce boards. Gangsaws typically include a number of parallel, circular saw blades located at precise intervals within a sawbox and, at the front of the sawbox, two chip heads (e.g., vertical drum chip heads) for removing excess wood from the outside of each cant. Cants may be transported in a straight line through the gangsaw using feed rolls on the upstream and downstream sides of the sawbox. Alternatively, the cants may be curve sawed. For example, the cant may be driven through the gangsaw along a curved sawing path during curve sawing. Alternatively, the sawbox may be moved during the cutting to produce a curved sawing path. In many sawmills, a cant scanner scans the incoming cants prior to processing by the gangsaw. A gangsaw computer optimizer then determines optimal locations for the chip heads and saw blades based on the scanned geometry of each cant.
Boards sawn by the gangsaw, as well as sideboards from the primary breakdown machine, may then be processed by an edger. The edger typically includes one or more saw blades for sawing along the length of the boards to achieve a chosen width. After edging, the boards are transported to a trimmer, where the boards can be trimmed to a final length. Both the edger and the trimmer may also have corresponding scanning systems and computer optimizers to determine how best to saw each piece of lumber.
At each processing station, an optimizer system makes determinations regarding the optimal way to saw each piece to maximize the value and volume of lumber produced from the raw logs. These optimizer systems are very complicated and expensive, and are also difficult to manage properly because of their complexity. If some portion of an optimizer system is not performing as expected, the sawmill can easily suffer a 1% to 4% loss of value until the problem is found and fixed. Thus, significant sums of money may be lost should any one optimizer system not function correctly.
Additionally, if some portion of the sawing system is not performing properly, the size of the pieces could be out of tolerance, causing the sawmill to suffer additional losses until the problems are found and fixed.
Thus, modern sawmills lack an effective way to determine if the processing stations are indeed functioning correctly and realizing optimal value from the raw resources. Consequently, there is a need for improvement.